Initiates in person, ignores online?

Hi.

I'm hoping someone here can help me. I'm a 21 year old female, never been in a relationship.

There's a customer who is my age, and over the last 6 months or so, I've developed a pretty serious crush.

He had a girlfriend up until a few weeks ago, but that apparently ended.

He's initiated conversation at work (eg. while I'm facing away from him, giving him an opportunity to walk past if he's just being nice when I see him) and I've watched him watch me (through periferals) until I make eye contact, at which point he smiles and asks how I'm doing.

Last Thursday, he came in and the following happened:
Him: What's new?
Me: (fearfearnervousvomitomgfear) OHnotmuchhow'boutyou?
Him: Oh, I'm finished school for a while, so I have more free time, hopefully I'll be able to come into the store more often. (said while browsing items in the front counters)
Me: (somesort of lame response)

So, I went home that night and relayed the conversation with my roommate, because I don't speak dude, but figured there wasn't any other way to interpret "I'll be in more often".
She told me to check his status, and that's when we found out he's single.

Sunday night, I sent the following:
"So, if you're bored on Monday, my friends and I go out to (karaoke bar) because we love to listen to bad renditions of the Backstreet Boys. Seriously though, we're always looking for new people, give me a shout if you're interested. (Cell number here)"

Monday came and went, and I didn't hear anything. I figured, okay, he's not interested, a girl can take a hint. Then, I find out that he was in the store Monday, not sure about Tues, and came in Wed and Thurs, both days I was OH SO MATURE and pretended not to see him, because I thought, seriously dude, you blow me off COMPLETELY and then come into my store EVERY DAY?
Numerous people have said that he 'clearly wanted to talk' and to 'give him a chance'.

Today when he came in, he waved and smiled, (I couldn't hide in my job and pretend not to see him, heh) and then we both sort of did an awkward "I'm going to walk around the store now" thing. I kept working and later on he walked down the aisle I was in and chatted, and kept coming back around my area when we were finished talking.

I seriously don't know how to read this guy.
In person, he seems to be leaning on the interested side, but I keep thinking he'd at least have responded that he was busy, had he read the message, or would have tried to interact via Facebook if he were.
My roommate thinks he may have deleted the message without reading it? My coworkers say he's really shy?

On the plus side, I no longer feel the automatic, debilitating nervousness after two days of being angry at myself/him... I probably have the best chance of being myself around him now.

Sorry for the novel, here's a synopsis:
tl;dr: mixed signals from a guy - he initiates conversation in person and I've caught him staring, but completely ignores online/outside methods of communication

Part of me worries that he's "just being nice".
I've been the one who is "just being nice" in the past, and it's an awkward situation... but then I think if he was "just being nice", he wouldn't go across the store just to ask me how a hat looked, right?

You should just casually ask him, "Hey, did you get my message the other day?" How did you send the message? Facebook message?

Do you know for a fact that he even checked it? My boyfriend has this habit of updating on Facebook for days and days, but then will get bored and stop for an entire week.

Don't start playing games as a way for him to come to you. Guys don't like feeling like they're being lured into a trap (well neither do women). Just be open and honest. Most guys look for those qualities in a girlfriend anyway.

Yeah, I sent it through Facebook message. He's updated his status a few times since, so I'm assuming he saw the message.

I'll try to stop with the games - it's hard to explain, and I don't want to sound like I'm making excuses, but in a way it felt safer. This is going to sound conceited, but I can usually tell if someone is interested - but if I'm interested in the guy, self-doubt creeps in and I don't trust my intuition at all.

He might feel the same way (self-doubt) and all, so try to have some empathy for his situation. A lot of guys have trouble broaching subjects and/or articulating themselves with someone they like. So, just ask him. Be approachable and cool. Hopefully he'll be cool about it too.

In the end, you'll never know what happened til you ask. You can guess and surmise and ask everyone else what could have possibly happened... but no one really knows except him. So just ask. If he keeps coming in and seems to want to talk, then it's open game to ask him about the message.

Since it's been a few days since you sent the message, after saying hi just say, 'oh by the way, did you see the msg I sent you a whle back?' You can probably tell more what he's thinking by the way he reacts.

It's tough navigating all the multiple ways of communicating with people these days... some people just aren't good at all of them. For me, I use facebook to post links to documentaries and news clips - that's it. I don't even read my messages immediately either - I usually wait til I have a lot of free time to go through them and respond back. In fact, I don't even go in the inbox because I don't want to see who it's from and be tempted to read it despite not having time. Because if I do read it, then it'll sit there, read but unreplied to, for ages til I remind myself that there's a message that needs to be responded to. Sounds complicated, right? So, honestly you NEVER know what really happened until you open up your mouth and just ASK. What have you got to lose - except more time and brain cells pondering a question with no answer.